The Cardio Myth?

In a previous post regarding Lance Armstrong’s marathon performance, I explored the heretical idea that there exists no general “conditioning” attribute; that aerobic capacity was activity-specific. With apologies to Greg Glassman, I’ll now explore the idea that the conventional idea of “cardio” simply doesn’t fly.

Forget about the layperson; speak to any doctor, personal trainer, exercise physiologist, or other health/medical professional and ask them to describe the concept of “cardio” to you. What they are likely to tell you is this:

“Cardio is short for cardiovascular exercise. It’s basically any type of activity that gets your heart moving, but for real benefit you’ve got to get your heart rate above 65% of its maximum. Most authorities like the AMA and ACSM say that you’ve got to do some cardio (at least 30 minutes) everyday. It strengthens your heart and lungs, and helps you lose weight.”

While well-intentioned, these are not true statements. here’s why:

1.) Cardio is not required for health.
What all the epidemiological studies (in particular, longitudinal ones like the Harvard Nurses Study, MRFIT, and the Blair study) on exercise and mortality show is that people who were moderately active lived the longest. What they don’t indicate is what “being active” means (aside from saying expended 2000 calories per week). You can “be active” by regularly strength training – the AHA says so. You can “be active” by walking to work in the morning, gardening on the weekends, playing with your kids in the evening – it doesn’t have to be 30 minutes on the treadmill.

Additionally, the people who “exercised” in those landmark studies did so because they chose to. Does that mean that they may have also engaged in other activities that prolonged their lives (such as eating healthfully, minimizing stress, etc.)? Likely. And there’s no way of separating this effect from their activities. So it’s possible (and probable) that these people lived longer because they led healthier lifestyles as a whole, not just because of the “exercise.”

2.) Cardio doesn’t strengthen your heart and lungs all that much.
Physiologists measure cardiovascular power by looking at VO2 max – the maximal ability of your body to utilize oxygen for aerobic metabolism (i.e., to perform work). The stark reality of VO2 max? It’s not that modifiable. Meaning, you can’t increase it much (less than 10%). Why?

Answer: Because in most healthy individuals, your cardiovascular system is already running at 100%. Your heart already is pumping at its optimal output (increasing heart size via training may not be the best idea for long-term health). Your lungs are already absorbing and transporting 100% of the oxygen molecules that they can into the bloodstream.

So how do you account for dramatic increases in performance?

Answer: Your muscles improve in their ability to take in and utilize oxygen in the bloodstream. The issue of “conditioning” is a muscular issue, not a cardiovascular one.

3.) Cardio doesn’t help you lose weight.
It simply doesn’t, if diet is ignored. Here’s my tired analogy:

Running 5 miles requires an output of roughly 500 calories. It takes a fit person roughly 45 minutes to run 5 miles.

By contrast, eating 500 calories can take less than 30 seconds, for any human being. In fact, my college buddies could probably chug 500 calories in less than one second.

If you don’t control for diet, there’s no amount of cardio that will help. Period.

BTW, at the low intensities most people exercise at, they’re likely burning just under 175-200 calories a shot. Just enough for a handful of almonds.

Don’t forget that cardio has a negative flipside:

1.) Prolonged exercise can actually damage the heart.
2.) Too much cardio causes muscle wasting and deleterious hormonal changes that increase likelihood of obesity.
3.) Too much cardio causes wearing away of joints and connective tissue, increasing likelihood of injury.

Now, if you’re a person who enjoys doing cardio, go right on ahead. I’m not telling you to stop running or kickboxing or biking. I myself live an active (overactive?) life – Brazilian Jiujitsu, snowboarding, mountain biking, general mayhem, etc. But I do all these things because I love doing them, not because I have to fulfill my “cardio requirement” for the day. My message is for those who thought it was a requirement for life. Believe me, if you stop doing cardio tomorrow, you won’t drop dead prematurely.

Well, to be honest, if cardio is the only exercise you’re doing, then maybe you will. Better start strength training instead – it’s safer and better for you in the long run.

Even the originator of “aerobics”, Dr. Kenneth Cooper has culled his recommendations somewhat, placing more emphasis on strength training and less emphasis on aerobics for health. Maybe one day he’ll even admit that saturated fat is good for you.

Bottom line: If you’re doing cardio because you think you have to for health or fat loss, you can stop now. It’s ok, you have my permission.

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